


CO(1)                    USER COMMANDS                      CO(1)



NAME
     co - check out RCS revisions

SYNOPSIS
     co [_o_p_t_i_o_n_s] _f_i_l_e ...

DESCRIPTION
     co retrieves a revision from each RCS  file  and  stores  it
     into the corresponding working file.

     Pathnames matching an RCS suffix denote RCS files; all  oth-
     ers  denote working files.  Names are paired as explained in
     ci(1).

     Revisions of an RCS  file  may  be  checked  out  locked  or
     unlocked.   Locking a revision prevents overlapping updates.
     A revision checked out for reading or processing (e.g., com-
     piling)  need  not  be  locked.   A revision checked out for
     editing and later checkin must normally be locked.  Checkout
     with  locking  fails  if  the  revision to be checked out is
     currently locked by another user.  (A  lock  may  be  broken
     with  rcs(1).)   Checkout  with  locking  also  requires the
     caller to be on the access list of the RCS file,  unless  he
     is  the  owner  of  the file or the superuser, or the access
     list is empty.  Checkout without locking is not  subject  to
     accesslist restrictions, and is not affected by the presence
     of locks.

     A revision is selected by options  for  revision  or  branch
     number,  checkin  date/time,  author,  or  state.   When the
     selection options are applied in combination,  co  retrieves
     the  latest revision that satisfies all of them.  If none of
     the selection options is specified, co retrieves the  latest
     revision  on the default branch (normally the trunk, see the
     -b option of rcs(1)).  A revision or branch  number  may  be
     attached  to  any of the options -f, -I, -l, -M, -p, -q, -r,
     or -u.  The options -d (date), -s (state), and  -w  (author)
     retrieve from a single branch, the _s_e_l_e_c_t_e_d branch, which is
     either specified by one of  -f,  ...,  -u,  or  the  default
     branch.

     A co command applied  to  an  RCS  file  with  no  revisions
     creates a zero-length working file.  co always performs key-
     word substitution (see below).

OPTIONS
     -r[_r_e_v]
          retrieves the latest revision whose number is less than
          or  equal to _r_e_v. If _r_e_v indicates a branch rather than
          a revision, the  latest  revision  on  that  branch  is
          retrieved.   If  _r_e_v is omitted, the latest revision on
          the default branch (see the -b  option  of  rcs(1))  is



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          retrieved.   If  _r_e_v  is  $, co determines the revision
          number from keyword values in the working file.  Other-
          wise,  a revision is composed of one or more numeric or
          symbolic fields  separated  by  periods.   The  numeric
          equivalent of a symbolic field is specified with the -n
          option of the commands ci(1) and rcs(1).

     -l[_r_e_v]
          same as -r, except that it  also  locks  the  retrieved
          revision for the caller.

     -u[_r_e_v]
          same as -r, except that it unlocks the retrieved  revi-
          sion  if  it was locked by the caller.  If _r_e_v is omit-
          ted, -u retrieves the revision locked by the caller, if
          there  is one; otherwise, it retrieves the latest revi-
          sion on the default branch.

     -f[_r_e_v]
          forces the overwriting of the working file;  useful  in
          connection with -q.  See also FILE MODES below.

     -kkv Generate keyword strings using the default  form,  e.g.
          $Revision:  5.7 $ for the Revision keyword.  A locker's
          name is inserted in the value of the  Header,  Id,  and
          Locker  keyword strings only as a file is being locked,
          i.e. by ci -l and co -l.  This is the default.

     -kkvl
          Like -kkv,  except  that  a  locker's  name  is  always
          inserted if the given revision is currently locked.

     -kk  Generate only keyword names in  keyword  strings;  omit
          their  values.   See  KEYWORD  SUBSTITUTION below.  For
          example, for the Revision keyword, generate the  string
          $Revision$ instead of $Revision: 5.7 $.  This option is
          useful to ignore differences due to  keyword  substitu-
          tion when comparing different revisions of a file.

     -ko  Generate the old keyword string, present in the working
          file  just  before it was checked in.  For example, for
          the Revision keyword, generate  the  string  $Revision:
          1.1  $  instead  of $Revision: 5.7 $ if that is how the
          string appeared when the file was checked in.  This can
          be  useful for binary file formats that cannot tolerate
          any changes to substrings that happen to take the  form
          of keyword strings.

     -kv  Generate only keyword values for keyword strings.   For
          example,  for the Revision keyword, generate the string
          5.7 instead of $Revision: 5.7 $.  This  can  help  gen-
          erate  files  in programming languages where it is hard



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          to strip keyword delimiters like  $Revision: $  from  a
          string.   However,  further keyword substitution cannot
          be performed once the keyword  names  are  removed,  so
          this  option should be used with care.  Because of this
          danger of losing keywords, this option cannot  be  com-
          bined  with  -l,  and the owner write permission of the
          working file is turned off; to  edit  the  file  later,
          check it out again without -kv.

     -p[_r_e_v]
          prints the retrieved revision on  the  standard  output
          rather  than  storing  it  in  the  working file.  This
          option is useful when co is part of a pipe.

     -q[_r_e_v]
          quiet mode; diagnostics are not printed.

     -I[_r_e_v]
          interactive mode; the user is prompted  and  questioned
          even if the standard input is not a terminal.

     -d_d_a_t_e
          retrieves the latest revision on  the  selected  branch
          whose  checkin date/time is less than or equal to _d_a_t_e.
          The date and time may be given  in  free  format.   The
          time  zone  LT stands for local time; other common time
          zone names are understood.  For example, the  following
          _d_a_t_es are equivalent if local time is January 11, 1990,
          8pm Pacific Standard Time, eight hours west of  Coordi-
          nated Universal Time (UTC):

               8:00 pm lt
               4:00 AM, Jan. 12, 1990           note: default is UTC
               1990/01/12 04:00:00              RCS date format
               Thu Jan 11 20:00:00 1990 LT      output of ctime(3) + LT
               Thu Jan 11 20:00:00 PST 1990     output of date(1)
               Fri Jan 12 04:00:00 GMT 1990
               Thu, 11 Jan 1990 20:00:00 -0800
               Fri-JST, 1990, 1pm Jan 12
               12-January-1990, 04:00-WET

          Most fields in the date and time may be defaulted.  The
          default  time  zone  is  UTC.   The  other defaults are
          determined in the order year, month, day, hour, minute,
          and  second  (most to least significant).  At least one
          of these fields must be provided.  For  omitted  fields
          that  are  of higher significance than the highest pro-
          vided  field,  the  time  zone's  current  values   are
          assumed.  For all other omitted fields, the lowest pos-
          sible values are assumed.  For example,  the  date  20,
          10:30  defaults  to 10:30:00 UTC of the 20th of the UTC
          time zone's current month and year.  The date/time must



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          be quoted if it contains spaces.

     -M[_r_e_v]
          Set the modification time on the new working file to be
          the  date  of  the retrieved revision.  Use this option
          with care; it can confuse make(1).

     -s_s_t_a_t_e
          retrieves the latest revision on  the  selected  branch
          whose state is set to _s_t_a_t_e.

     -w[_l_o_g_i_n]
          retrieves the latest revision on  the  selected  branch
          which was checked in by the user with login name _l_o_g_i_n.
          If the argument _l_o_g_i_n is omitted, the caller's login is
          assumed.

     -j_j_o_i_n_l_i_s_t
          generates a new revision which is the join of the revi-
          sions  on _j_o_i_n_l_i_s_t. This option is largely obsoleted by
          rcsmerge(1) but is retained for  backwards  compatibil-
          ity.

          The _j_o_i_n_l_i_s_t is a comma-separated list of pairs of  the
          form  _r_e_v_2:_r_e_v_3,  where  _r_e_v_2 and _r_e_v_3 are (symbolic or
          numeric) revision numbers.  For the initial such  pair,
          _r_e_v_1 denotes the revision selected by the above options
          -f, ..., -w.  For all other  pairs,  _r_e_v_1  denotes  the
          revision  generated  by  the previous pair.  (Thus, the
          output of one join becomes the input to the next.)

          For each pair, co joins revisions _r_e_v_1  and  _r_e_v_3  with
          respect  to  _r_e_v_2.  This  means  that  all changes that
          transform _r_e_v_2 into _r_e_v_1 are applied to a copy of _r_e_v_3.
          This  is  particularly  useful if _r_e_v_1 and _r_e_v_3 are the
          ends of two branches that have _r_e_v_2 as a common  ances-
          tor.   If  _r_e_v_1<_r_e_v_2<_r_e_v_3  on  the same branch, joining
          generates a new revision which is like _r_e_v_3,  but  with
          all  changes  that  lead  from _r_e_v_1 to _r_e_v_2 undone.  If
          changes from _r_e_v_2 to _r_e_v_1  overlap  with  changes  from
          _r_e_v_2  to  _r_e_v_3,  co  reports  overlaps  as described in
          merge(1).

          For the initial pair, _r_e_v_2 may be omitted.  The default
          is  the common ancestor.  If any of the arguments indi-
          cate branches, the latest revisions on  those  branches
          are  assumed.   The  options  -l  and -u lock or unlock
          _r_e_v_1.

     -V_n  Emulate RCS version _n, where _n may be 3, 4, or 5.  This
          may  be useful when interchanging RCS files with others
          who are running older versions of RCS.   To  see  which



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          version  of  RCS  your correspondents are running, have
          them invoke rlog on an RCS file; if none of  the  first
          few  lines  of  output contain the string branch: it is
          version 3; if the dates' years have just two digits, it
          is  version 4; otherwise, it is version 5.  An RCS file
          generated while  emulating  version  3  will  lose  its
          default  branch.   An RCS revision generated while emu-
          lating version 4 or earlier will have a timestamp  that
          is  off  by up to 13 hours.  A revision extracted while
          emulating version 4 or earlier will  contain  dates  of
          the  form  _y_y/_m_m/_d_d  instead of _y_y_y_y/_m_m/_d_d and may also
          contain different white space in the  substitution  for
          $Log$.

     -x_s_u_f_f_i_x_e_s
          Use _s_u_f_f_i_x_e_s to characterize RCS files.  See ci(1)  for
          details.

KEYWORD SUBSTITUTION
     Strings of the form $_k_e_y_w_o_r_d$ and $_k_e_y_w_o_r_d:...$ embedded  in
     the   text   are   replaced   with   strings   of  the  form
     $_k_e_y_w_o_r_d:_v_a_l_u_e$ where _k_e_y_w_o_r_d and  _v_a_l_u_e  are  pairs  listed
     below.   Keywords may be embedded in literal strings or com-
     ments to identify a revision.

     Initially, the user enters strings of  the  form  $_k_e_y_w_o_r_d$.
     On  checkout,  co replaces these strings with strings of the
     form $_k_e_y_w_o_r_d:_v_a_l_u_e$.  If a revision containing  strings  of
     the latter form is checked back in, the value fields will be
     replaced during the next checkout.  Thus, the keyword values
     are  automatically updated on checkout.  This automatic sub-
     stitution can be modified by the -k options.

     Keywords and their corresponding values:

     $Author$
          The login name of the user who checked in the revision.

     $Date$
          The date and time (UTC) the revision was checked in.

     $Header$
          A standard header containing the full pathname  of  the
          RCS  file,  the  revision  number,  the date (UTC), the
          author, the state, and the locker (if locked).

     $Id$ Same as $Header$,  except  that  the  RCS  filename  is
          without a path.

     $Locker$
          The login name of the  user  who  locked  the  revision
          (empty if not locked).



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     $Log$
          The log message supplied during checkin, preceded by  a
          header   containing  the  RCS  filename,  the  revision
          number, the author, and the date (UTC).   Existing  log
          messages  are  _n_o_t replaced.  Instead, the new log mes-
          sage is inserted after $Log:...$.  This is  useful  for
          accumulating a complete change log in a source file.

     $RCSfile$
          The name of the RCS file without a path.

     $Revision$
          The revision number assigned to the revision.

     $Source$
          The full pathname of the RCS file.

     $State$
          The state assigned to the revision with the  -s  option
          of rcs(1) or ci(1).

FILE MODES
     The working file inherits the read and  execute  permissions
     from  the RCS file.  In addition, the owner write permission
     is turned on, unless -kv is set or the file is  checked  out
     unlocked and locking is set to strict (see rcs(1)).

     If a file with the name of the working file  exists  already
     and  has  write  permission,  co aborts the checkout, asking
     beforehand if possible.  If the existing working file is not
     writable or -f is given, the working file is deleted without
     asking.

FILES
     co accesses files much as ci(1) does, except  that  it  does
     not need to read the working file.

ENVIRONMENT
     RCSINIT
          options prepended to the argument  list,  separated  by
          spaces.  See ci(1) for details.

DIAGNOSTICS
     The RCS pathname, the working  pathname,  and  the  revision
     number  retrieved are written to the diagnostic output.  The
     exit status is zero if and only if all operations were  suc-
     cessful.

IDENTIFICATION
     Author: Walter F. Tichy.
     Revision Number: 5.7; Release Date: 1991/08/19.
     Copyright 8c9 1982, 1988, 1989 by Walter F. Tichy.



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     Copyright 8c9 1990, 1991 by Paul Eggert.

SEE ALSO
     ci(1),  ctime(3),  date(1),   ident(1),   make(1),   rcs(1),
     rcsdiff(1), rcsintro(1), rcsmerge(1), rlog(1), rcsfile(5)
     Walter  F.  Tichy,  RCS--A  System  for   Version   Control,
     _S_o_f_t_w_a_r_e--_P_r_a_c_t_i_c_e & _E_x_p_e_r_i_e_n_c_e 15, 7 (July 1985), 637-654.

LIMITS
     Links to the RCS and working files are not preserved.

     There is no way to selectively  suppress  the  expansion  of
     keywords,  except by writing them differently.  In nroff and
     troff, this is done by embedding the null-character \&  into
     the keyword.

BUGS
     The -d option sometimes gets confused, and accepts  no  date
     before 1970.




































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